This study has investigated the expression of the p53 tumour suppressor gene in 41 cases of primary nasopharyngeal carcinomas (NPC) using the p53 monoclonal antibody BP53-12. Moderate p53 expression was found in 54% and strong expression in 12% of the specimens. There was no correlation between p53 expression and any of the clinicopathological parameters or survival. Surprisingly, three research groups have investigated p53 mutations in NPC and found no fresh tumour specimens to contain p53 mutations in exons 4-8 of the gene. It may be argued that as p53 overexpression has been demonstrated in 70% of the patients investigated in this study, that the mutations lie outside the 4-9 exon region. We are in the process of testing this hypothesis.